It is of great importance that the lip of sharp-edged tools of various types, such as knives, chisels, etc., has the correct cutting angle in order for the tool to function in the correct way and with good control of its movement without the lip being damaged. The correct cutting angle naturally depends on the quality of the steel, the type of tool, the hardness of the wood and how hard one works with the tool. Experience of these variables determines the angle that is correct for each occasion.
A practical way of setting a certain cutting angle, chosen because of the reasons mentioned above, for grinding the tool has not been available. When grinding tools by hand today, there is only one type of template provided with notches or angular-shaped grooves of different angles in which the lip of the tool can be inserted to determine or estimate the cutting angle.